Moved TUN device creation to pre-fork

src/tun.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"os"
 	"sync/atomic"
 )
 
@@ -15,6 +16,7 @@ const (
 )
 
 type TUNDevice interface {
+	File() *os.File            // returns the file descriptor of the device
 	Read([]byte) (int, error)  // read a packet from the device (without any additional headers)
 	Write([]byte) (int, error) // writes a packet to the device (without any additional headers)
 	MTU() (int, error)         // returns the MTU of the device